A rotor, drum or similar system, rotating along one axis is usually a very important part of many machines. Such similar rotational parts exists in electric motors, various mills, fans, turbines, grinding machines, washing machines and many similar machines. In many machines, the balance is provided by adjusting the uniformity of the weight distribution of these rotational bodies along their rotational axis during manufacturing, where otherwise such an unbalance may cause unwanted vibrations in the machine which can even cause damage. But in some cases, the rotating part of the machine can be under the influence of varying imbalance forces. A washing machine spinning at high speeds, a grinding machine with worn out grind stone, a mill with unevenly worn parts are some examples of such machines. The said invention of the smart balancing system brings effective solution for such imbalance problems faced in these machines. A washing machine is chosen as an example in order to explain the said invention. The application of this invention for other machines will be similar to various washing machine types described below and therefore not explained in detail in this description.
In our present time, automatic washing machines are in use at homes, touristic locations, hospitals, residence homes, military organisations, organisations which provide professional cleaning services and many other areas. Besides the use of these machines for cleaning purposes, the use of such machines are continuously increasing in the textile industry for garment washing, stone washing and garment dying processes. Due to increasing capacities in the cleaning and textile industries, the number of machines to be used per unit area tends to increase and this encourages the washing machine manufacturers to design and manufacture larger capacity machines. Larger machines mean larger front loading doors and larger diameter wash drums. The larger diameter drums, spinning at high speeds creates new problems to be solved. Today, various washing machines are produced ranging from 4-6 Kg used in our homes, 6-150 Kg used in professional cleaning services and 100-500 Kg used in textile industry which are bedded with shafts either from one end or both ends of the rotating drum.
In rotary drum washing machines, high spin speeds are usually required in order to achieve efficient spinning results at around 300-400 g centrifugal forces. The factors which affect water extraction from garments in centrifugal spinning method are; drum diameter, drum rotation speed, the permeability and the temperature of the garments and the thickness of garments on the perforated surface of the drum. Efficiency in extracting water is not directly proportional with the increased centrifugal forces due to higher drum rotation speeds. Increasing centrifugal forces, on one hand, forces the mass of water towards the drum circumference but at the same time, it squeezes all the garments along the drum""s inner surface and these wet textile fibres under this force forms a plastic type layer causing resistance against extracted water. It is more efficient to increase the inner drum surface area as this will reduce the garment thickness along the drum surface, causing better extraction. Increasing the inner drum surface usually results in deeper drum depths over longer rotational axis. The increased drum length makes it more difficult for the garments to be equally distributed against the inner drum surface which causes high imbalance along the rotational axis of the drum. Even if this is achieved, very small differences in weight distribution along the rotational axis causes damaging vibrations at high spin speeds. This imbalance problem is the major design criteria in high spin speed washing machines. Today""s classic systems employs techniques where the drum assembly is placed on springs or air cushions and uses air or hydraulic type pressurised cylinders or shock absorbers in order to minimise the effects of vibration on the main body structure.
Another method of reducing the effects of vibration is to increase the weight of the mass, under the effects of acting imbalance forces. As a result, the mass which the imbalance forces has to move is increased, reducing the magnitude of vibration. This requires the use of additional weights on the total construction of the washing machine. These additional weights on the machine usually exceeds 50% of the normally required mechanical construction weight of the machine. Apart from this, the bearings used in order to connect this heavy mass of rotating mechanism to the main body construction has to be chosen larger than it should be necessary due to the high vibrational forces caused by the imbalance of the rotational system.
The vibration absorption systems used on the existing machines have limited use. By this reason, the garments have to be distributed along the inner drum surface as good as possible before the extraction process. In order to achieve this, the drum rotation speed first has to be increased to a level where the centrifugal forces just start to overcome the earth""s gravitational forces. During this constant rotational speed or speed increase, the garments near to the inner surface of the drum sticks to the inner surface and starts to rotate together with the drum. As the garments, which cling to the drum as a result of the centrifugal forces stars to get pressed towards the inner surface, the cling diameter will be reduced gradually. When all the garments sticks to the inner surface and starts rotating with the drum, the distribution is said to be completed. If the garment distribution is not achieved properly, the extraction process will halt during spin process due to unacceptable vibration levels of the machine and the distribution process will commence again. These xe2x80x9cre-startsxe2x80x9d cause loss of time and energy as well as reduction in the machine capacity.
Many balancing techniques have been developed so far for washing machines, in order to eliminate the unwanted inbalance forces. These are generally mechanical systems which make use of the acting imbalance forces. These systems introduced some improvements in small capacity machines but due to their complex construction, they required maintenance and increased the over all cost of the machine and therefore not widely used. The said mechanical balancing systems weren""t also successfully applied for higher capacity industrial washing machines. U.S. Pat. No. 2,534,267/268/269, Kahn, U.S. Pat. No. 3,117,962, Starr""s patents are some examples for the said balancing systems. The U.S. Pat. No. 5,280,660 Pellerin-Gaulter patent, which is most similar to the said invention in theory, has benefited from the ribs inside the rotating drum and tried to eliminate the imbalance forces by forcing water into these ribs through separate channels. This method divides the 360xc2x0 of drum circumference into three locations with 120xc2x0 apart and forces the correct amount of water into one or more ribs opposite to the imbalance force vector until this vector is eliminated. This balancing system has, to a great amount, solved the balancing problems in the larger industrial type washing machines and with the additional precautions, high speed spinning was achieved. But with this method, it was impossible to eliminate the balancing weights completely. The generated imbalance vectors can be at different points along the drum axis and the magnitude and direction can also vary. For drums with small depth/diameter ratio, the above mentioned method could provide satisfactory results but as the depth of the drum is increased, the imbalance becomes almost impossible to be compensated with the said method. Besides, the dynamic movements of the balancing fluid in the ribs itself causes varying imbalance weights in the system. With this method, the rotational axis of the drum must be highly horizontal. If this condition is not satisfied, the balancing fluid in the ribs will tend to collect to one side along the rotational axis in the ribs and cause further imbalance which will be difficult to compensate. The best method of balancing a rotational mass is to compensate the mass from both ends of its rotational axis. This way, an imbalance force vector formed along the rotational axis of the mass can be compensated with smaller counter-weights compared to its magnitude. Therefore, smaller counter-balance weights encountered at each end of the rotational axis can eliminate the imbalance of the drum. This is the only way to balance the system precisely. The better way of increasing the capacity of machines is to increase the depth/diameter ratio of the drum where such balancing problems of the said system is eliminated with the said method. The Pellerin-Gaulter balance system, in actual fact, utilises an older method of forcing balancing fluids into three separate equal volumes in the rotating drum independently through separate fluid canals and pipes. At present day, many applications of this idea is used, differing only in the way of control systems and sensing methods. But in the said new invention, the balancing method, the design of the balancing drum/drums and the method of injecting the balancing fluids into the balancing drums differ from the others to a great extend. The other systems require intelligent electronic control units which have to sense and calculate the direction and the magnitude of the imbalance vectors and determine the amount of balancing fluid to be forced into each particular rib. The cost of such control units will specially be significant for domestic type washing machines where competition and economics are at utmost importance. Another disadvantage of this balancing system by utilising such volumes in the drum is the loss of useful volume within the drum. Water naturally collects within these volumes during normal washing process. The chemical concentration in washing water is important during washing process. The amount water filled into these volumes means less chemical concentration and more energy use if heating is used. If the imbalance force vector is formed at such an angle so that the counter-balance weight has to lie in somewhere in between the two ribs, then balancing fluids have to be forced into both ribs. In this case, since the total resultant counter-balance force vector is the sum of the two force vectors of the two ribs in the opposite direction of the imbalance force vector, the magnitude of each of these force vectors have to be larger than the imbalance vector to be eliminated. The worst case condition is when the imbalance force vector is in the same direction with one of the ribs. In this case the counter-balance weight has to be in between the opposite two ribs, therefore equal amount of balancing fluids has to be forced into these two ribs. The counter-balance weight vector in the opposite direction of the imbalance force vector is half of the centrifugal force vector created. Therefore, the amount of balancing fluid mass to be forced into each corresponding rib has to be equal in magnitude to the imbalance force vector. In fact, only the same amount of mass needed to be inserted on the opposite direction of the imbalance force vector in order to eliminate it. Vector sum balancing method used in the washing machines requires twice the volume needed, in order to eliminate the imbalance weights. The balancing system described in the said invention uses both vector summing and direct opposite force vector method, therefore requires at least 50% less volume compared to the existing systems. Another requirement of these balancing systems is to keep the total washing times at optimum levels. After the washing process, the washing or rinsing water within these balance cells has to be released completely. At spin speeds, the imbalance of the rotational system has to be eliminated at the shortest possible times and after the spin process, the used balancing fluids has to be disposed without coming in contact with the washed garments. The balancing method to be developed should allow construction of any required size machine and should also be able to eliminate any kind of imbalance force vectors within the system.
The said dynamic balance invention allows the construction of any required size machine. In domestic washing machines, due to economical reasons, the system functioning makes use of the dynamic movements initiated by the acting imbalance forces. But in the industrial type washing machines, the cost savings on the machine construction due to balancing systems makes it feasible to use computers and sophisticated sensing systems for precise balancing results.
In the industrial washing machines, after the distribution process is completed, the balancing computing system starts monitoring the imbalance force vectors separately from both ends of the drum and determines the direction and the magnitude of the counter-balance force vectors to be created in the front and the rear dynamic balancing drums in order to eliminate the cause of imbalance in the system. Therefore the disorder of the weight distribution within the rotational system is eliminated and high rotational speeds will be possible without any problems.
On the load/unload side of the main drum, another cylindrical drum with a diameter greater or equal to the main drum is fitted. The name of this drum will be called as xe2x80x9cbalancing drumxe2x80x9d here on, and only a small surface of the balancing drum is slotted open and it is divided into smaller cells or pockets of equal volume. The number of these cells/pockets can be increased according to the acceptable level of balancing, required in the machine. A second balancing drum similar to the one fitted on the front side of the main wash drum is also fitted on the rear side. A water jet system is also fitted exactly opposite to the slotted open inlet of each balancing drum units at each end. The balancing function computer control system determines the magnitude and the direction of the counter-balance weight to be created in each particular balancing drum and controls the balancing fluid injector valves in order to fill the correct amount of balancing fluid into particular balancing cells/pockets in the drum closer to the imbalance vectors to be eliminated by controlling the valves fitted on the pressurised balancing fluid pipes. The fluids entering the balancing cells/pockets will start to rotate together with the drum under the effect of the centrifugal forces. Therefore it is possible to balance the rotating drum independently from front and rear ends. There are two different types of valves used in the fluid injecting system. The computer system first uses the larger capacity valve or valves in order to roughly create the required counter-balance weights in the opposite direction of the imbalance forces to be eliminated. After reaching a lower level of balance, the smaller capacity valve or valves are used in order to complete the balancing action.
In case said invention is applied to the washing machines, there will be no need for extra weights used for reducing the effects of the imbalance forces on the machine and therefore the need for the springs, shock absorbers, air cushions and such similar systems will be reduced to a great extend. Also, since the high level of vibrations will not be acting any more, the need for over sized bearings, the drum shaft and the drum construction will be reduced and become more economical. As a result, the machine construction will be simpler and more economical than before.